Plywood is a multi-talented material, and there’s much more to this adaptable wood than meets the eye. It can be used for a wide range of DIY projects ranging from home improvements through to renovations.
However, there is a wide range of types, grades, and finishes that determine how the plywood is used. It can be used to build furniture, cabinets, and shelves, which are on display, it can be painted or stained and even used to build structures where it will never be seen. But, these scenarios all have a bearing on how, or if, it needs sanding.
Here, you‘ll find the answers you need regarding when you should sand plywood, and what you need to do in order to achieve the finish you want.
Types and grades of plywood
Plywood comes in many guises including the size, type of wood and grades. Knowing the differences between the type and grade will help you understand how to sand the plywood.
“There are many kinds of plywood," says Kevin Keen, owner of Keens Buildings. "The variances depend on the type of wood, the quantity of plies, the glue used, and where it will be utilised.”
The most popular option for DIY projects is typically softwood, and as Kevin shares, “softwood plywood, is usually made of pine or fir and is often used in framing and building.”
Another common option is hardwood; this is often used for framing as well, but it can also be used for other projects. “People utilise hardwood plywood, like birch or oak, to make cabinets and furniture,” explains Kevin.
Beyond hardwood and softwood plywood, there are more specialist options too.
“Marine plywood is watertight and has no internal spaces, making it great for projects that will be exposed to a lot of moisture," says Kevin, "while exterior-grade plywood employs water-resistant adhesives for outdoor applications.
"Plywood that has been treated with pressure resists rot and bugs, while plywood treated with fire retardants is less likely to catch fire," he adds.
Try this softwood plywood for all types of projects
A superior softwood, smooth-appearance plywood with no open defects. It offers high strength, rigidity and good durability. Ideal for furniture, roofing, flooring and stud walls.
Plywood grades
As well as the different types, plywood also comes in different grades, ranging from A to D, with grade A being the highest, based on the quality of the materials, appearance, and strength.
Common grades are AB, B and BB. The finer grades will typically need less sanding.
AB grade is the highest quality, characterised by a consistent appearance with minimal or no pin knots. This is ideal for projects where the plywood surface is visible, such as cabinets or furniture.
B grade has the natural appearance of wood and can include knots up to 35mm in size. This is ideal for painting and staining. Finally, C-grade plywood is ideal for projects such as building stud walls where the surface doesn’t need to be seen, but still requires strength.
Kevin has been in the industry for 25 years and handles everything, from the distribution and installation of portable structures to financing and manufacturing. He can speak with authority on every aspect of construction.
Best way to sand plywood
Combining an electric sander with the right sandpaper grade is the popular choice for sanding plywood, says Kevin Keen. “An electric sander is the best choice for most plywood surfaces since it works faster and produces an even finish.”
A random orbital sander is the ideal choice if you're wondering which type of sander. Why? “A random orbital sander avoids swirl marks and is easier to handle than a belt sander,” explains Kevin.
To help ensure your plywood surface stays as even as possible when sanding, there are a few tips you can use.
“Light pencil marks on the surface help track sanding progress and keep the work even,” suggests Kevin, and when the pencil marks disappear, move on to the next section of the surface. "Don't press too hard," he adds, "as plywood layers can thin unevenly if over-sanded.”
Plywood edges need more attention too, explains Kevin. “Hand sanding is better for edges and corners where more control is needed.” Make sure to use a sanding block like this SATC Hand Sanding Block from Amazon, with a fine 120-grit sandpaper.
If painting plywood after sanding, fill the edges with a quality wood filler and rub down with fine sandpaper first.
Try these tools for sanding plywood
A corded orbital sander with a low vibration design and a 280W motor that rotates at 12000rpm for a superior finish. Boasts a standard 125mm hook and loop pad and a variable speed dial.
Hook and Loop 125mm sanding pads. Available in packs of 100 with grits ranging from 40 to 1200. Or choose a multi-grit pack with varying grits ranging from 40 to 600.
Complete the job by using this fine sandpaper to smooth corners and edges before painting your sanded plywood
Sandpaper grits to use
Which sandpaper grit you use will depend on the type of plywood and the state of the surface. "Hardwood plywood needs finer grits to eliminate scratches, whereas softwood and external grades can be sanded with medium grits,” says Kevin Keen.
If the plywood has rough spots or splinters (which are typically found on the edges), start with 80-120 grit sandpaper. To finish, “use 150 to 180 grit next to make the surface smooth so that paint or varnish may stick," he says.
If painting plywood, start by sanding the wood and adding a primer. When the primer is dry, use a fine 240-grit sandpaper to gently sand the surface. Apply this between coats to achieve a super-smooth painted surface.
FAQs
Can you buy plywood that is pre-sanded?
Yes, there are specialist types of plywood that can come pre-sanded. “You can buy cabinet-grade or sanding-grade plywood that is already sanded and ready to finish,” confirms Kevin, but these are rarely used in most DIY or home renovation projects.
The common options of softwood and hardwood plywood don’t come pre-sanded, so they will need to be sanded before it is painted, stained or sealed.
What is sanding sealer?
If you are working on a plywood project where the surface needs to be treated to get a extra finish, such as polish, lacquer or wax, a sanding sealer (like this Chestnut CSS500 Cellulose Sanding Sealer from Amazon) can be used to help ensure that these finishes are applied evenly and look good.
Sanding is a key part of the preparation for a host of DIY projects including painting wooden doors and painting floorboards. If you’re painting floorboards, you’ll need a specialist sander, so make sure you read our guide to the cost of sanding a wood floor.
